Filter



FIG. 1 is a top plan view of a filter showing my new design, the bottom plan view being the same as the top shown;

FIG. 2 is a side-elevational view of one side thereof; the opposite side being the same as the side as shown;

FIG. 3 is an elevational view taken from one end thereof; and

FIG. 4 is an elevational view taken from the end opposite that shown in FIG. 3. 

The ornamental design for a filter, substantially as shown and described. 